The invention relates to a method and a device for manufacturing adhesively bound printed products formed of a book block and a cover, in which the book blocks are each conveyed past processing stations of the adhesive binding device in one of several circulating clamps of an adhesive binding device for processing and applying glue to their backs. Subsequently, a cover is supplied with synchronized timing to the back which has been provided with glue. In that case, after the cover has been combined with the book block, a measuring procedure for determining a mutual actual position of the cover relative to book block is provided.
In the industrial manufacture of adhesively bound printed products, such as magazines, catalogs, paperbacks or similar products, in a first step printed sheets are gathered into loose book blocks, and are subsequently processed in an adhesive binder in the back area thereof, and are provided with glue and glued together with the cover. In this connection, quickly running adhesive binders have a plurality of clamps which are arranged with regular spacings and circulate in a closed track, wherein the loose book blocks are clamped and transported in the longitudinal direction of the backs from a feeding station to a release station. The drive of the clamps can be effected through pulling means driven by a drive wheel, wherein the clamps are attached to the pulling means, or directly through racks arranged at the clamps, wherein the racks are drivable through a drive gear. By means of stationary processing stations arranged between the feeding station and the release station, such as, for example, back processing stations, gluing stations, cover stations, and pressing stations, the book blocks protrude slightly with their back areas downwardly from the clamps and are processed while they are being conveyed. One of the last processing stations in an adhesive binder is the cover station. The accuracy by which the covers can be placed in the longitudinal direction of the backs relative to the book block constitutes a significant quality feature of a bound printed product. After being supplied to the clamps, the book blocks are precisely aligned in the longitudinal direction of the back. By means of a conveyer circulating in a closed track the covers are conveyed to the merging location of cover and book block and are pressed by a pressing station from below against the book block back and on the sides. The drive of the cover conveyer is connected either mechanically or is connected through its own drive synchronously to the drive of the clamps. The achievable accuracy of cover relative to book block is significantly impaired by defects in the drive means, primarily the pulling means of the drive means, caused by manufacturing inaccuracies and wear. In addition, the accuracy can be negatively influenced by changing production conditions, such as production speed, glue film thickness, glue application, temperature or the force with which the covers are pressed.
CH 475098 A5 describes a method in which the position of the covers in relation to the book blocks is controlled by an adaptation of the supply units of the covers to the clamps. The supply units are arranged at a cyclically operating pressing station and are aligned relative to the clamp before the cover is merged with the book block. A relatively short time window is available for this alignment procedure, so that, in the case of high cycle numbers, the cover can be deformed by high accelerations and, thus, the expected alignment accuracy can no longer be achieved,
CH 586115 A5 describes a method in which higher cycle numbers are possible by referencing a cover conveying chain directly at a clamp, so that the cover can be aligned relative to the book block. Even if the accelerations and the resulting negative effects on the printed products are reduced, this method is not suitable for cycle numbers above 12,000 cycles/h.
In DE 10221542 A1 a device is disclosed in which the clamps and at least one processing station are drivable independently of each other. In this connection, a measuring system for determining the position of the clamps or of the book blocks is provided in the vicinity of this processing station for the control thereof in the sense of a positioning task. As a result, a processing station, for example, the supply of covers to the clamp or to the book block can be aligned.
When using the solutions according to the prior art, deviations of the covers relative to the book block, caused by tolerances in the drives and pulling means for driving the clamps and the feeding of the covers, car only be prevented before they are combined. Deviations which occur during and/or after the combining of the covers with the book blocks, cannot be determined or compensated by means of devices according to the prior art. Such deviations can be caused, for example, by changes of parameters such as, production speed of the adhesive binder, the film thickness or the application temperature of the adhesive and the pressing force of the cover against the book block.